1. Field of the Invention
The invention relates to a tissue-specific gene promoter, and in particular, to a promoter useful for anther-specific expression in plant, and application thereof.
2. Description of the Prior Art
In the improvement of crop's characteristics, or in relative studies utilizing plant gene transfer technology, conventionally, a gene to be expressed or studied is constructed downstream of a specific promoter sequence and the gene to be studied is then expressed or modulated with the activation ability of said promoter. Among conventional techniques, over-expressing the target gene is mostly driven by the CaMV 35S promoter in plant. Unfortunately, CaMV 35S promoter is not a tissue-specific promoter in that it can not over-express a target gene at a specific plant tissue. Therefore, how to make over-expression of a target gene at a specific plant tissue or in a particular period is the key point to modulate a gene's expression.
Accordingly, for researches of bioscience or developments of the biotechnical industry, how to screen out promoters with different specificity to drive the expression of a transferred target gene at a target site and bring out a maximum benefit of gene transfer is the important topic for improving the development of biotechnical industry and increasing the economical benefit of crops.
At present, molecular biologists have found a number of promoters having spatial (i.e., specific cell or tissue) or temporal (i.e., at different growth and development stages) specificities, or promoters inducible by a specific substance such as UV-B or chemical substances, that can be used to activate the expression of a transferred target gene to achieve the purpose of modulating gene expression.
In genetic breeding, “heterosis” is a very important research trend for obtaining crop with better character. Heterosis is to be understood to mean that a first hybrid progeny (F1 progeny) generated from the hybridization of two parents has a character with average performance better than either parent. In the course of hybridization, if the crop of interest is a selfing crop, the parent should be subjected first to artificial castration and then pollination to increase in order to avoid selfing, which increases production cost. For example, in the breeding study of Cruciferae vegetables, selfing lineage of self incompatibility is currently used mostly to carry out F1 seed collection. Nevertheless, several bottlenecks such as instability of hybridization rate, difficulty in the propagation of selfing parent line, low seed collection due to selfing depression, as well as the unlikeliness for superior parent to have self incompatibility exist yet. To activate particular genes that may result in male sterility or ability to silence pollination-associated gene by means of an anther-specific promoter shall be an important contribution for improving character by applying biotechnology.
Though many studies have found promoters with anther- or pollen-specific activation activity, such as potato (Lang et al., 2008), tomato (Bate and Twell, 1998), maize (Hamilton et al., 1998), rice (Gupta et al., 2007), petunia (Garrido et al., 2006), antirrhinum (Lauri et al., 2006), lily (Okata et al. 2005), cabbage (Park et al., 2002) and the like, no study on gene promoter associated with an orchid has been reported so far.
Oncidium Gower Ramsey is an important export cut flower for Taiwan. Its flower has a bright yellow color. Since customers desire visual aesthetic feeling and prefer novel flower colors, flower color becomes one of the important factors determining values in the flower crop industry and articles. In view of the foregoing, the inventors attempted to isolate genes associated with the biosynthesis of yellow pigment from Oncidium, and screened out promoters with tissue-specificity through the analysis of a promoter of aureusidin synthase gene.
Also, in view of the importance of developing promoters with distinct specificity for the biotechnology industry, the inventors had been devoted to improve and innovate, and, after intensive studying for many years, has developed successfully a anther-specific expression promoter in plant, and application thereof according to the invention.